Intrusion Countermeasure Programs, or ICPs for short, are security programs that protect their system from computer viruses and unauthorized programs. ENCOM's ICP's are commanded by the mighty Kernel. When they "see" someone or something that is damaging surrounding programs, they automatically try to derez the program. However, this can be a fault because they cannot tell the difference between a malicious program or a harmless program or user; any program or user that is "unauthorized" (i.e. not allowed to be in that part of the computer) will be derezzed on sight.

All ICP's fight with a Disc Primitive weapon at the very least. Some ICPs come equipped with shields that block any non-explosive projectile, while others wield a Sequencer disc.

ICPs have different circuitry color depending on what system they originated from. ENCOM ICPs have red circuitry, Internet ICPs have blue circuitry, and ICPs from fCon have purple circuitry. The circuitry usually corresponds to the color scheme of the environment the ICP is in.

An ICP can call in for reinforcement from a Sec Rezzer. These devices spawn in additional ICPs to help neutralize the threat. A program or user with the correct permissions can deactivate the sec rezzer. These rezzers also match the color of the ICP's of that system.